Resuscitation describes the use of external efforts to assist or restore the breathing of a person whose breathing has ceased or become impaired, by forcing oxygen containing gas into the lungs of the person under pressure, and then providing an interval of time for the lungs to deflate and gas to escape. Some forms of resuscitation such as mouth to mouth require no form of specialized resuscitation equipment. However where available it is generally preferred that resuscitation be performed with the assistance of specially designed resuscitation equipment.
A resuscitation device in widespread use is the "squeeze-bag" type resuscitator. This device has a resilient, manually compressible bag that stores a quantity of oxygen containing gas, usually air or oxygen enriched air, which is forced out of the bag under pressure by squeezing the bag. When squeezing of the bag ceases and the bag is released it regains its shape and in the process refills itself with gas. Gas from the bag is ultimately delivered to the victim or patient through an inhalation mask that covers the nose and mouth of the patient, or through another device such as an endotracheal or tracheostomy tube. Modern resuscitation devices use a resuscitation valve to direct gas from the bag and into the patient.
Another type of resuscitation device uses a pneumatically-actuated cylinder and piston to depress the sternum while synchronizing the delivery of gas to the patient's lungs.
The resuscitation valve in these devices controls gas flow between the patient and the valve. When the bag is compressed the valve performs the basic function of directing gas from the bag into the mask. In addition, the valve provides a non-rebreathing function that vents gas exhaled by the patient to the atmosphere and prevents the exhaled gas from entering the bag. Should the patient begin unassisted breathing the valve permits inhalation of gas from the bag only. Of course, the valve must not vent gas from the bag when inspiratory resistance in the patient causes airway pressure to rise. Accordingly the resuscitation valve must perform a multiplicity of functions.
These multiple functions provide numerous advantages and are therefore found in a variety of resuscitation devices that include mouth to mask resuscitation equipment as well as bag type resuscitators. A major function of a resuscitation valve is isolation of the gas supply source from the patient. With the valve in place exhaled air, liquids or vomitus from the patient will not enter the bag or in the case of mouth-to-mask resuscitation devices, the person supplying the gas. Another function of the valve is that it must cause the patient to inhale gas only from the bag. This function is particularly helpful when administering oxygen-enriched gas to the patient by preventing the patient from rebreathing exhaled gas with its lower oxygen concentration and higher carbon dioxide concentration.
For a resuscitation valve to provide satisfactory service it must meet a number of criteria. The valve must operate reliably. Reliable operation demands that a variety of valve elements perform the necessary sealing functions while not unduly restricting gas flow or burdening normal breathing by the patient. It is particularly desirable that valve elements needing a relatively large degree of movement to achieve sealing be avoided since the need for movement is a source of possible malfunction. A number of more recent valve designs use flexible membranes to achieve sealing, however reliability may be impaired when these membranes require excessive deformation or flexing to open and close.
Furthermore, the valve elements must be compact so that the overall size of the valve remains small in relation to the rest of the resuscitation apparatus. Ideally the valve would also be capable of continued operation when liquids and vomitus expelled by the patient enter the valve. As a result, resuscitation valves that provide all or most of these desired functions tend to be complicated in construction and relatively high in price.
Consequently, the considerable cost associated with the majority of resuscitation valves has dictated their reuse. Before reuse, a complete cleaning and disinfection of the valve must be done to assure sanitary conditions and proper operation. Thorough cleaning of a resuscitation valve means at least a partial disassembly. Although the need for disassembly and cleaning of the valve is a disadvantage in itself, it poses additional hazards since the valve may be unknowingly damaged or reassembled improperly during the cleaning process. As a result an additional testing procedure is needed to make sure that the resuscitation devices are operating properly after cleaning. The need to clean the resuscitation valves also adds to the less obvious but substantial problem of resuscitator equipment loss.
Portable resuscitators are in common use and found in many hospital departments, ambulances, paramedic units, clinics, first aid kits, and doctor's offices. In a typical hospital situation, the respiratory care or central supply unit is responsible for cleaning all resuscitation equipment. Since a number of departments use bag resuscitators they all depend on the department doing the cleaning to have an adequate surplus of bags to meet their needs. When removal for cleaning leaves an inadequate supply of bags in a given area, bag stealing between departments commonly occurs and can lead to a shortage of bags in a department. Unfortunately bag stealing does not stop with interdepartmental raiding. Other bag users that are in and out of the hospital may see the hospital as a convenient source of resuscitation bags and take hospital-owned bags.
It has been recognized that disposable resuscitation devices would have the advantage of not requiring cleaning. However, some disposable devices that have been proposed do not provide all of the functions of the reusable valves. In addition, at least one such valve incorporates a mask integral with the valve so that the cost of such a device is still rather high.